docs: web platform + clean URLs + dark/light mode (#37)

* chore(docs): replace d2 diagram pipeline with mermaid

Remove docs/_diagrams/ and d2 build step from Makefile. The HTML
template already initialises mermaid.js; diagrams are now inline
code fences rendered client-side.

* docs(architecture): add mermaid diagram + web/CDP platform docs

Replace SVG img tag with inline mermaid flowchart showing both native
(Maestro sidecar + in-app SDK) and web (Chrome CDP) paths. Update
Processes, Transports table, and per-step cycle sections.

* docs(design-principles): update principles 1-4 for web platform

Principles 1, 2, 3, and 4 referenced Maestro and native-only concepts.
Add web/CDP context and update driver-is-an-interface to name both
sidecar and chrome implementations.

* docs(manual): add web prerequisites and folio-web example

Update --platform flag to list android, ios, web. Add web prerequisites
section (Chrome, no SDK needed) and folio-web quick-start to
getting-started.

* chore(gitignore): untrack inspect dist/index.html build artifact

index.html is regenerated by vite on every build with a new content hash,
making it permanently dirty. Only .gitkeep is needed for //go:embed to
compile on a fresh checkout. Also remove duplicate dist/* line and stale
d2 diagram ignore entries.

* feat(docs): click-to-zoom for mermaid diagrams

* docs(architecture): change diagram layout from LR to TB

* docs(getting-started): link npm and Maven Central package headers

* update docs root

* docs(spec): rewrite npm package README

Update usage example to current API, drop stale version-compatibility
and license sections.

* build(docs): output pages as pagename/index.html for clean URLs

Split DOCS_OUT into INDEX_OUT (index.md files stay as index.html) and
PAGE_OUT (all other pages become pagename/index.html). The __ROOT__
depth computation already handles the extra directory level correctly.

* chore(docs): update sidebar links to directory-style URLs

* docs: update cross-links from .html to directory-style paths

* ci(docs): remove d2 install step

* feat(docs): dark/light mode toggle

Add theme toggle button (top-right, fixed). Persists preference in
localStorage; falls back to prefers-color-scheme. Flash-free via inline
script in <head> that sets data-theme before first paint.

* fix(docs): fix inspect image path broken by directory URL restructure

* feat(docs): click-to-fullscreen for all article images

* fix(inspect): allow AssetsFS override in ServerOptions; drop unused request param from serveIndex

* fix(inspect): use in-memory FS in tests so TestAssets_FallbackToIndexHTML passes without web build

docs/manual/getting-started.md

@@ -8,10 +8,17 @@ Install the CLI, link the SDK into your debug build, run a spec.
 
 ## Prerequisites
 
-- An Android emulator with API level 30 or newer.
+**Android / iOS:**
+
+- An Android emulator with API level 30 or newer (or a connected device).
 - The app under test built as a debug variant with the sanderling Android SDK linked in.
 - `adb` on your PATH.
 
+**Web:**
+
+- Chrome installed. sanderling drives it via CDP; no other setup required.
+- No in-app SDK needed.
+
 Run `sanderling doctor` to check the host environment.
 
 ## Install
@@ -22,13 +29,13 @@ Run `sanderling doctor` to check the host environment.
 curl -fsSL https://raw.githubusercontent.com/priyanshujain/sanderling/master/install.sh | bash
 ```
 
-### Spec package (npm)
+### Spec package ([npm](https://www.npmjs.com/package/@sanderling/spec))
 
 ```sh
 npm install --save-dev @sanderling/spec
 ```
 
-### Android SDK (Maven Central)
+### Android SDK ([Maven Central](https://central.sonatype.com/artifact/io.github.priyanshujain.sanderling/sdk-android))
 
 ```kotlin
 dependencies {
@@ -38,6 +45,8 @@ dependencies {
 
 ## Your first run
 
+### Android
+
 The repo ships a working sample at `examples/folio`, a Kotlin Multiplatform app with a TypeScript spec under `sanderling/spec.ts`. Install `just`, then from `examples/folio`:
 
 ```sh
@@ -53,6 +62,18 @@ AVD=Pixel_7 just test
 
 Persistent settings can live in a `.env` alongside the justfile (`AVD=Pixel_7`, `DURATION=5m`, and so on).
 
+### Web
+
+The repo also ships a web sample at `examples/folio-web`, a React/Vite app with the same domain logic. From `examples/folio-web`:
+
+```sh
+just test      # starts Chrome, runs the spec
+```
+
+No emulator or SDK setup needed.
+
+### Trace output
+
 When the run ends, the trace lands in `sanderling/runs/<timestamp>/`:
 
 ```
@@ -62,6 +83,6 @@ runs/2026-04-18T12-34-56/
 └── meta.json
 ```
 
-Browse it with `sanderling inspect` (see [inspect](./inspect.html)), or read `trace.jsonl` step by step.
+Browse it with `sanderling inspect` (see [inspect](./inspect/)), or read `trace.jsonl` step by step.
 
-Next: [writing specs](./writing-specs.html).
+Next: [writing specs](./writing-specs/).